Can you Boot into Safe Mode by pressing the function key F8 repeatedly on startup. If you can then try a System Restore.
If you cant you will have to Boot from the Vista DVD and go to the Recovery Console.
When you get to the recovery console follow these instructions.
Type CD\ then Enter
Then cd system~1\_resto~1 then Enter
Type dir then Enter
When you hit enter it will list all the restore points folders like rp1, rp2 ??.. If the restore points have more than one page then u have to keep on hitting the key to view the last restore point folder. You will have to choose the second to last option folder
Type cd rp {the second to the last restore point no. } (Note: Example: cd rp9, if rp9 is the second to the last restore point where the last restore point no. is 10
Then type cd snapshot
Now the command prompt will look like this c:\system~1\_resto~1\rp9\snapshot
Type: copy _registry_machine_system c:\windows\system32\config\system
Press enter
Then type: copy _registry_machine_software c:\windows\system32\config\software
Then type exit
If you get an access denied error when doing the above, then do the following at the recovery console:
Type CD\ then press Enter
Type cd windows\system32\config then press Enter
Type ren system system.bak then press Enter
Type exist press Enter
Your PC will reboot, go back into the Recovery Console and then you have access
If you still cannot get access in anyway to your installation in the recovery console then your SAM database files are corrupt. There is no way you can restore these with the recovery console. You may need to do a fresh install
http://neosmart.net/blog/2008/windows-vista-recovery-disc-download/
You can use the Hard Drive Makers Testing Utility to Test the Drive
Hitachi / IBM - DFT "Drive Fitness Test"
http://www.hgst.com/hdd/support/download.htm
Works with all manufacturers
Western Digital "Data Lifeguard"
http://support.wdc.com/download/index.asp#dlgtools
Works with WD drives only
Fujitsu "FJDT"
http://www.fel.fujitsu.com/home/drivers.asp?L=en&CID=1
Works with fujitsu models only
Samsung "hutil"
http://www.samsung.com/Products/Hard...ties/hutil.htm
Compatability unknown...
Seagate "Seatools"
http://www.seagate.com/support/seatools
Works with Seagate drives only
If you have failures you will have to replace the drive.
< edit >
If it is still under warranty have it repaired. ;)
